August Krogh was a Danish physiologist born on November 15, 1874. He is best known for his research on the regulation of blood flow and the role of capillaries in the body. His work contributed significantly to our understanding of how oxygen is delivered to tissues, which has implications in fields like medicine and exercise physiology. In 1920, Krogh was awarded the Nobel Prize in Physiology or Medicine for his discoveries related to the function of the circulatory system. He also made important contributions to the study of respiration and metabolism, influencing both scientific research and practical applications in health and fitness.